Understanding the Role of a Silane-Coupling Agent in Bio-Based Polyurethane Nanocomposite-Coated Fertilizers

Abstract

Bio-based polyurethane (PU)-coated controlled release fertilizers are attracting a lot of attention; however, generally they have poor properties, so it is difficult for them to meet the agricultural needs. Herein, γ-aminopropyl triethoxy silane (KH550) was first used with nanosilica (NS) to prepare bio-based PU nanocomposite-coated urea (KSPCU). The coating microstructures and nutrient controlled release behaviors of KSPCU were investigated and compared with those of unmodified NS containing PU nanocomposite-coated urea (SPCU) and bio-based PU-coated urea (PCU). The KSPCU with KH550 exhibited an excellent controlled release performance. Its nutrient release longevity exceeded 105 d, which was nearly 6 times greater than that of PCU and 2 times more than that of SPCU, and it was much longer than that of PCU reported in previous research at a coating rate of 3 wt %. A series of characterization methods combined with water resistance capacity and porosity measurements confirmed that a hydrogen bond was formed by the reaction between the nanoparticle and PM200, the nanoparticle was bonded on the macromolecular chain, and KH550 in the coating increased the cross-linking degree, which were beneficial to slowing down the nutrient release of the KSPCU. The innovative application of KH550 on bio-based PU-coated fertilizers will provide a new coating technology for improving their controlled release property.

Bio-based Polyurethane Based on a Dynamic Covalent Network with Damage Tolerance for Controlled Release of Fertilizers

“…As shown in Figure A and Figure S4, compared with the FTIR spectra of the raw monomer, new peaks of N–H groups (3324 cm –1 ) and CO groups (1735 cm –1 ) were only observed in the FTIR spectra of BPCF coating, confirming the formation of BPU. In addition, the peak of −NCO groups (2259 cm –1 ) disappeared completely in the FTIR spectra of BPCF coating, indicating a complete reaction between the −OH groups and isocyanate . Similar results of BPCF coating were obtained by FTIR characterization of the TBPCF coating containing different BDO contents.…”

Stearic Acid Treatment Enhancing Corrosion Resistance of Biomimetic-Deposited Calcium Phosphate Dihydrate Coating on Medical Degradable Magnesium Alloy

“…In FTIR spectra (Figure b), there were no obvious bands in the spectrum of the Mg alloy, while absorption bands of Si–O–Si at 1106 cm –1 , Si–O at 1020 cm –1 , and −CH at 2935 cm –1 appeared after treatment with silane, illustrating that the SCA was combined on the surface of the Mg alloy and formed a coating. − The bands detected from 1072 to 920 cm –1 after biomimetic deposition, which corresponded to the P–O stretching of the HPO 4 2– group, confirmed the formation of DCPD coating . In contrast, in addition to the retained bands for phosphate, the newly emerged bands at 2920, 2844, and 1557 cm –1 after treatment with stearic acid and sodium stearate represented C–H, C–C, and −COO–, respectively, which were the characteristic functional groups of stearic acid and sodium stearate, demonstrating the modification of DCPD coating by stearic acid and sodium stearate …”

Poly(vinyl alcohol)/sodium alginate polymer membranes as eco‐friendly and biodegradable coatings for slow release fertilizers

“…According to the Ehrlich reaction, the nitrogen concentration was measured at the wavelength of 430 nm with a UV-visible spectroscopy (UV-2550; Shimadzu, Kyoto, Japan) using 4-(dimethylamino) benzaldehyde as an indicator. 36 Moreover, the initial nitrogen content in the PCU granules was known. Hence, the released nitrogen content is the difference value between the initial and the left nitrogen content.…”